1. Field of the Invention
The present invention relates generally to a slide assembly and more specifically to a mechanism for determining the sequence in which the individual members of the slide assembly extend and/or retract upon opening or closing of the slide assembly.
2. Description of the Related Art
Slide assemblies are typically mounted on opposing sides of a movable object, such as a drawer, to allow the object to be extended from within a cabinet, or other support structure, in order to be accessible. There are two common types of slide assemblies. The first type includes two segments which slide with respect to one another, one being fixed to the enclosure and the other fixed to the movable object. The maximum extension of a two segment slide is necessarily less than the length of either segment, in order to maintain engagement between the two segments.
The other common type of slide includes at least one intermediate segment, which is in sliding engagement with both the object-mounted slide segment and the enclosure-mounted slide segment. In a three segment slide, an outer segment is affixed to the enclosure, an intermediate segment slides with respect to the outer segment, and an inner segment slides with respect to the intermediate segment and is fixed to the movable object. Thus, the intermediate segment is detached from both the surrounding cabinet and drawer, or other object.
The additional slide segment in a three segment slide creates a stronger, stiffer slide assembly in comparison with a two segment slide. Furthermore, in some arrangements, the inner slide segment can be extended from within the outer slide segment at least its entire length. This type of slide assembly is commonly referred to as an xe2x80x9cover-travelxe2x80x9d slide. Thus, by utilizing an over-travel slide assembly, the movable object may be completely withdrawn from the enclosure.
To avoid damage to the slide assembly, it is desirable that first the intermediate slide extends with respect to the outer segment and then the inner segment completes the full extension of the slide. Many sequenced slide assemblies rely on an arrangement which induces friction between the inner slide segment and the intermediate slide segment so that the inner and intermediate slide segments extend together until the intermediate segment reaches full extension. However, when the slide assembly is carrying a load, extraneous sources of friction between the outer slide segment and the intermediate slide segment may overcome the intended, sequencing friction and allow the inner slide segment to extend before the intermediate segment. Thus, in an actual use environment, such friction slide assemblies often fail to provide reliable sequencing action.
Other sequencing arrangements utilize gravity-assisted latch mechanisms, which pivot under the influence of gravity to lock two of the slide segments together. However, because these types of sequencing arrangements rely on gravity, they are not effective when the slide assembly is inverted. Accordingly, a single slide design cannot be used to support both sides of an object, as the slide assemblies have to be inverted relative to one another so that the outer slide segments face the enclosure and the inner slide segments face the supported object. If a gravity-assisted latch mechanism is used, right-hand side specific and left-hand side specific slide segments must be provided, which are typically mirror images of one another. This results in increased manufacturing costs and requires pairing of right-hand slides with left-hand slides. Therefore, given the drawbacks of the prior art, a need exists for an improved slide sequencing assembly.
Another example of a prior latch mechanism is illustrated in FIG. 1 and described in greater detail in U.S. Pat. No. 5,551,775 to Parvin. The slide assembly 1 of Parvin includes an inner slide segment 1a, an intermediate slide segment 1b and an outer slide segment 1c telescopingly engaged with one another, as is well known in the art. A latch member 2 is pivotally connected to the intermediate slide segment 1b to pivot about an axis 3. A spring arm 2a extends from a forward end of the latch member 2 and is capable of flexing with respect to the main body portion 2b of the latch member 2. A tab 4 is affixed to the inner slide segment 1a and may be configured to contact the spring arm 2a when the inner slide segment 1a is fully retracted with respect to the intermediate slide segment 1b. Accordingly, the latch member 2 is rotated about the pivot axis 3 such that a corner 2c of the latch 2 engages an opening 5 in the inner slide segment 1a. Due to the interference between the corner 2c and the opening 5, extension of the inner slide segment 1a results in extension of the intermediate slide segment 1b. 
The latch 2 also includes a perpendicular tab 2d that extends through a window 6 in the intermediate slide segment 1b. When the intermediate slide segment 1b nears a fully extended position, the tab 2d engages an actuator (not shown) on the outer slide segment 1c. The actuator has a ramped contact surface that lifts the tab 2d as the latch 2 moves along the actuator (i.e., as the inner 1a and intermediate 1b slide segments are extended). As a result, the latch 2 is rotated such that the corner 2c is disengaged from the opening 5 and the inner slide segment 1a is free to extend relative to the intermediate slide segment 1b. 
The Parvin reference states that this structure permits the latch 2 to couple the inner slide segment 1a and the intermediate slide segment 1b for extension without the assistance of gravity, due to the interaction between the tab 4 and the spring arm 2a. As a result, the slide assembly 1 may be inverted such that a single slide design may be used to mount both the right-hand and left-hand side of a drawer, or other object. However, the Parvin slide assembly 1 relies on the relative positioning of the inner 1a and intermediate 1b slide segments to achieve this result. Accordingly, once the inner slide segment 1a is extended, even slightly, relative to the intermediate slide segment 1b, the latch 1 is subject to rotation due to gravity. As a result, the latch 1 cannot be used for other sequencing functions, such as locking the intermediate segment 1b in an extended position, in both an upright and inverted orientation. Furthermore, as is described in greater detail below, the latch 1 relies on precise positioning of the tab 4 of the inner slide segment 1a. As a result, manufacturing of the slide assembly becomes more costly. Accordingly, a need exists for a slide sequencing arrangement that provides reliable operation in both an upright and an inverted position, and does not rely on relative positioning of the individual slide segments to assume an operational position.
Accordingly, preferred embodiments provide an improved slide sequencing arrangement particularly adapted to use a minimum of parts for inexpensive manufacture and assembly. Advantageously, the assembly is particularly adapted for use in three member slides wherein the inner segment is only slideable once the middle segment has been fully extended, thereby minimizing damage to the slide assembly. The preferred arrangement also locks the intermediate segment in its fully extended position until the inner slide segment is substantially completely retracted with respect to the intermediate slide segment upon closing of the slide assembly. Preferably, the sequencing assembly is operational, independent of gravity, despite the relative positions of the individual slide members. Further, the assembly is preferably adapted to achieve these advantages within a relatively narrow cross-sectional envelope.
A preferred embodiment is a slide assembly including an outer slide segment, an intermediate slide segment and an inner slide segment. The intermediate slide segment is telescopingly engaged with the outer slide segment and is moveable between a retracted position and an extended position with respect to the outer slide segment. The inner slide segment is telescopingly engaged with the intermediate slide segment and is moveable between a retracted position and an extended position with respect to the intermediate slide segment. A sequencing latch is pivotally connected to the intermediate slide segment. A spring member has a first end and a second end and is configure to exert opposing forces from the first and second ends. The first end of the spring member acts on the intermediate slide segment and the second end of the spring member acts on the latch. Thereby, the latch is biased into mechanical engagement with the inner slide segment to lock the inner slide segment substantially in the retracted position with respect to the intermediate slide segment when the intermediate slide segment is in the retracted position. An actuator is fixed with respect to the outer slide segment and includes a ramp surface being configured to engage the latch when the intermediate slide segment is substantially in the extended position. Further extension of the intermediate segment causes the latch to rotate and release the inner slide segment from the retracted position.
A preferred embodiment is a slide assembly including an outer slide segment, and intermediate slide segment and an inner slide segment. The intermediate slide segment is telescopingly engaged with the outer slide segment and is moveable between a retracted position and an extended position with respect to the outer slide segment. An inner slide segment is telescopingly engaged with the intermediate slide segment and is moveable between a retracted position and an extended position with respect to the intermediate slide segment. A sequencing latch connected to the intermediate slide segment. The latch has a first end defining a retaining surface and a release surface. The retaining surface being configured to lock the inner slide segment substantially in the retracted position with respect to the intermediate slide segment when the intermediate slide segment is in the retracted position. An actuator is fixed with respect to the outer slide segment and is configured to engage the latch to release the inner slide segment from the retracted position when the intermediate slide segment is substantially in the extended position. The actuator additionally comprises a stop surface, the latch being configured to engage the stop surface to secure the intermediate slide segment into the extended position. A portion of the inner slide segment is configured to engage the release surface of the latch during retraction of the inner slide segment to bias the latch out of engagement with the stop surface and thereby permit retraction of the intermediate slide segment.
A preferred embodiment is a slide assembly including an outer slide segment, an intermediate slide segment and an inner slide segment. The intermediate slide segment is telescopingly engaged with the outer slide segment and is moveable between a retracted position and an extended position with respect to the outer slide segment. The inner slide segment has at least one transverse flange defining an opening and is telescopingly engaged with the intermediate slide segment. The inner slide segment is moveable between a retracted position and an extended position with respect to the intermediate slide segment. A sequencing latch is connected to the intermediate slide segment. A spring member is arranged to apply opposing forces on the intermediate slide segment and the latch. The spring member biases the latch within the opening to lock the inner slide segment substantially in the retracted position with respect to the intermediate slide when the intermediate slide is in the retracted position. An actuator is fixed with respect to the outer slide segment and is configured to engage the latch. Wherein further extension of the intermediate segment rotates the latch to release the inner slide segment from the retracted position when the intermediate slide segment is substantially in the extended position.